Certain transition and heavy metal ions pose increasing environmental and health risks. For example, as the use of Ni—Cd batteries increases, so does the prevalence of nickel and cadmium ions in manufacturing, disposal, and environmental contamination. It has long been known that mercury ions are a persistent and prevalent health risk, with a large percentage of the populace exposed to the risk. The same goes for lead ions, found in peeling paint on older buildings. These increasing incidences result in increasing exposures and internalization of these ions within individuals.
Thus there exists a need for increasingly sophisticated methods for the detection and quantitation of certain heavy metal and transition metal ions in a variety of samples, ranging from groundwater and soil to inside human cells. In the biomedical research field, luminescence-based probes of alkaline earth metal cations such as calcium have been of enormous benefit. To date there have been some examples of luminescence-based detection methods developed for heavy metal and transition metal ions. However these existing methods rely upon substandard compounds which lack specificity, dynamic range, sensitivity, and applicability to field use. The present invention addresses these shortcomings by describing novel luminescence-based materials that are very useful for the detection and quantitation of certain metal ions such as cadmium(II), lead(II), mercury(II), and nickel(II).